1. Field of the Invention
The invention relates generally to the packaging industry. In more specific aspects, the invention relates to packaging and methods for forming packaging that have tamper evident closures to indicate that tampering with the packaging may have occurred.
2. Description of the Related Art
Many types of end user or consumer products are packaged in bags that can be opened and resealed without any signs of the bag having been opened. An example of such a type of bag that is commonly used for user products is a pinch bottom open mouth type of bag. Many improvements have been made to the pinch bottom bag to various properties of the bags, such as improved performance, more environmentally friendly versions, and improved sealability of the bag.
Improvements to different aspects of the bags have been made to help the bags better protect the products contained within the bags. For example, U.S. Pat. No. 3,958,749 titled “Gusseted Pinch Bottom Breakaway Pouch Bag” by Goodrich describes a multiwall bag having a plastic inner tube heat sealed at one end and manufactured integral with an outer tube housing that provides sift proof, leak proof, odor retention and sanitary packaging for a bulk product, and for subsequent uncontaminated withdrawal of the packaged products. Although the bag in Goodrich adequately protects the contents within the bag, if the bottom seal is opened and then subsequently closed, there is no way to tell if tampering of the bag has occurred.
Another improvement to bags, such as pinch bottom bags, can be found in U.S. Pat. No. 4,609,571 titled “Primer System for Grease Repellant Papers” by Tytke. Prior to Tytke, oil and grease resistant substrates used to make the bag oil and grease resistant did not accept adhesives very well, which made it difficult to economically seal bags made with these types of substrates. Tytke describes the use of a stryrene/butadiene rubber primer used to increase the surface affinity and penetrability of adhesives on substrates treated for oil and grease resistance. Once again, this improves the bag for use with end user products. If the bottom seal of the bags described in Tytke were to be subject to tampering, there still would not be a way to determine if this had occurred.
Even more environmentally friendly pinch bottom bags have been made, as described in U.S. Pat. No. 5,529,396 titled “Environmentally Friendly Pinch Bottom Bag Assembly and Method of Making” by Pryor et al. Pryor describes a pinch bottom bag assembly in which a removable plastic bag is contained within a protective outer bag that will not leave any plastic scraps trapped within the protective outer bag once the inner bag has been removed from the outer bag. No mechanism exists to assist users in determining if these bags have previously been opened either.
Numerous other improvements have been made to bags, such as being able to reclose the open mouth of the pinch bottom open mouth bags, as described in U.S. Pat. No. 4,946,289 titled “Reclosable Open Mouth Bag” by Bolling et al. Easy opening bags are described in U.S. Pat. No. 4,557,385 titled “Bag with Easy Open Line of Perforations” by Robinson and U.S. Pat. No. 6,213,644 titled “Multiply Bag with Tear Strip Opening Mechanism” by Henderson et al.
The inability to tell if the bags have been previously opened, however, continues to create a concern for many users since the contents of the bags could be the subject of tampering. Although many improvements have been made to various aspects related to bags, efforts to provide tamper evidence for bags are still needed. With the increased number of incidents of end user products being poisoned or otherwise modified, a need still exists for users to be able to tell if the package has previously been opened before. A further need exists for the tampering evident mechanisms to be easy to incorporate into the existing packaging processes and to be economical.